Hydrogen Carbon Cleaning for Subaru Legacy Touring Wagon (EJ20 Engine) in Ishikawa
- 孝一 田﨑
- 1 day ago
- 6 min read
Headline: Hydrogen Carbon Cleaning on a 340,000km Subaru Legacy Touring Wagon (EJ20) in Ishikawa
Body Text: We recently had the pleasure of performing a hydrogen carbon cleaning service on a customer's beautiful Subaru Legacy Touring Wagon here in Ishikawa Prefecture!
This particular model is powered by Subaru’s legendary EJ20 engine—a 1,994cc horizontal-opposed (Boxer) 4-cylinder DOHC 16-valve turbo engine. In its prime, this powerplant pushes out a maximum output of 260 ps (206 kW) at 6,400 rpm and a maximum torque of 35.0 kg·m (343 N·m) at 2,000 rpm.
What makes this vehicle truly impressive is its current mileage: approximately 340,300 kilometers (over 211,000 miles)!
The Challenge: Failing Emissions Tests
The owner brought the car to us after a pre-inspection at a local dealership revealed that the exhaust emission levels had exceeded the legal regulation limits required for the Japanese vehicle inspection (Shaken).
While our shop has extensive experience successfully restoring diesel engines that fail emissions or emit black smoke, treating a gasoline engine for this specific issue was a new challenge for us. We transparently shared this with the customer, and with their kind understanding and approval, we proceeded with the treatment.
The Process: Tailored Hydrogen Gas Injection
Before starting, we conducted a thorough pre-check of the engine sound, idling vibrations, and exhaust pressure from the muffler to establish a baseline.
Once the preparations were complete, we began injecting the hydrogen gas. We started at a conservative flow rate of 100 L/h to carefully monitor the engine's real-time response. As we confirmed the engine was stable, we gradually increased the hydrogen volume to maximize the carbon removal process.
Scroll down to read our live impressions during the treatment!
↓↓↓ [In-Progress Treatment Impressions]
↓↓↓ [In-Progress Treatment Impressions]
5 Minutes into the Service: Initial Observations Just 5 minutes after starting the hydrogen injection, we noticed the exhaust gas becoming slightly damp. To check the exhaust pressure, I held my hand over the muffler exit. While the overall pressure felt adequate, there was a slight pulse or uneven wave in the exhaust flow. To investigate further, we revved the engine and monitored the tachometer (RPM gauge). When dropping back down to idle from 2,500 rpm, the needle fluctuated slightly. We proceeded with the cleaning, focusing heavily on whether this idling instability would improve.
10 Minutes in: Water Vapor Begins As we carefully monitored the engine's behavior, we gradually increased the hydrogen gas flow rate. Ten minutes into the treatment, water vapor started blowing out of the tailpipe. This is a great sign that the hydrogen is successfully binding with the carbon buildup inside the combustion chambers and turning into moisture. We continued to fine-tune the hydrogen volume.
20 Minutes in: Engine Sound & Vibrations Subside By the 20-minute mark, a noticeable change occurred: the engine sound and idling vibrations began to noticeably quiet down. The boxer engine was running significantly smoother. With the engine stabilized, we locked in the hydrogen injection rate at this optimal level.
40 Minutes in: Dramatic Improvement in Exhaust Flow & Idle Response At 40 minutes, we blipped the throttle a few times to test the response. Holding my hand over the muffler exit once again, the slight wave and uneven pulse we felt at the beginning was completely gone. The exhaust was now flowing smoothly and consistently. Even better, the tachometer fluctuation had disappeared. When returning from 2,500 rpm down to idle, the needle dropped smoothly and locked perfectly into place without any shudder or bounce.
50 Minutes in: Clean Combustion Approaching the 50-minute mark, the exhaust gas exiting the tailpipe felt dry again, indicating that the internal cleaning was highly effective and the engine was achieving much cleaner, complete combustion. The actual exhaust note had also transformed into a crisper, healthier sound.
65 Minutes in: Service Completed After 65 minutes of adjusting the hydrogen flow and monitoring the vehicle, the engine idle, sound, and exhaust output were completely stable. With the EJ20 engine running better than it had in years, we concluded the service.
↓↓↓ [Customer Impressions Post-Treatment]
↓↓↓ [Post-Service Customer Review & Feedback]
We received some fantastic feedback from the owner a few days after the service!
Emissions Test Results: The owner took the car back to the dealership to recheck the exhaust emission levels. This Legacy features a dual-exit exhaust system; one side passed with flying colors, and the other side successfully dropped just within the legal limit. The car officially passed the emissions inspection!
Driving Performance Impressions: The difference on the road was immediately noticeable. When cruising at 60 km/h at around 1,500 rpm, just a slight press on the gas pedal allows the engine to rev smoothly all the way up to 3,500–4,500 rpm.
Response & Efficiency: Throttle response has improved significantly, and the car is also getting better fuel economy (MPG).
The customer was thrilled to feel the tangible benefits of the treatment and relieved that the emission numbers are back within the required regulation limits.
A Note from Our Shop
While our shop regularly handles black smoke issues and emissions failures on diesel vehicles, this was our very first time performing a hydrogen carbon cleaning to fix a failed emissions test on a gasoline-powered car. Since we’ve had great success bringing high-emission diesel engines back into legal compliance, we felt confident it would work on a gasoline engine too—but we are incredibly relieved and happy to see these official results!
This particular Subaru Legacy has been highly customized with aftermarket ECU tuning and upgraded intake/exhaust systems, making this project an incredibly valuable learning experience for our team as well.
With hydrogen cleaning, the full effects often continue to peak after driving the vehicle for a little while longer as the loosened carbon fully clears out. We advised the owner to keep an eye on how it behaves over the next few weeks.
If you notice anything else or have any questions, please feel free to reach out to us anytime. Thank you so much for choosing our shop for your vehicle's care. We look forward to serving you again in the future!
At e-BLUE, we never treat any two vehicles the same. We carefully inspect and monitor the specific condition of each individual engine throughout the entire process, custom-tuning the hydrogen delivery rate to match its needs. This tailored approach drastically maximizes the overall cleaning efficiency and delivers far superior results.
If you have any questions or would like to learn more about our services, please feel free to reach out to us at any time.
Thank you for your continued support of e-BLUE and our Hydrogen Gas Carbon Cleaning services. We look forward to helping you restore your engine's peak performance!
For bookings and inquiries, you can reach us by phone or email. If you send us an email, we will get back to you as soon as we review your message. Thank you for your patience!
Phone: +81-90-8262-1052
Email: eblue2022kt@gmail.com
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